Process of manufacturing hydrofluoric acid.



UNITED Y STATES Patented March 22,5934.

PATE T ,OFFICE.

CHARLES A. noinii us, OF New YORK, N. Y.

PROCESS OF MANUFACTURING HYDRQFLUORIC ACID.

SYECIFICATION forming part of Letters Patent No. 754,978 dated. March 22, 1904- Applicetion filed July 31, 1962.' Serial F0. 117,808. (No specimens.)

To all whom, it may concern:

Be itknown that 1, CHARLES A. Donnnus, a

citizen of the United States, residing in the borough of Manhattan, in the city'and State of New York, have invented a new and useful Process of Mund' cturing Hydrofluoric Acid, of which the following s u specification.

The object or my invention is to produce hydrofluoric acid which shall be free from the hydrofluorsilicic acid with which owing to the presence of silica in either floor-spar or kryolith thecommerciul hydrofluoric acid obtained from these natural ores is usually cont-amineted. Siliconfiuorid can be obtained either from these natural ores or from artificial products and easily be made to yield hydrofluorsilicic acid. Such hydroiluorsilicic acid may be. used for my process.

My improved process consists in treating with an excess of finely-ground bauxite or kaolin either h'ydrofluorsilicic acid or a mixture of hydrofluorsilieic acid and hydrofluoric aciduntil a perfectly neutral solution of alu rninium fiuorid is thereby obtained, the fluorsilieate which is first formed being decomposed by the excess of uluminious material to yieid: the fluorid and a precipitate of silicic acid, which, together with insoluble substances, is separated by filtration. The aluminium fluorid may be obtained in crystalline form, either by cooling or by evaporation. VFhen dry, the fiuorid is placed in an iron retort and there heated to redness. This retort has an outlet which connects with a leaden-condenser. When the fluorid is red-hot, it is subjected to the action of superheated steam, which is introduced into the retort, Hydrofluoric acid of great purity is rapidly evolved and condenscd. Aluminium oxid remains in the retort. The yield of acid from the fluorid is practically theoretical. I have similarly ob mined and treated other metallic iluorids.

Other apparatus than a retort has been successively employed by me, with the results above mentioned, and therefore I do not re-' strict my process to the use of a retort 1n which to subject the fluorid to the action of superheated steam.

i In treating the hydrofluorsilicic acid or the mixture thereof and hydrofluoric acid heat facilitates the action.

Calcined alnminious materials may be used.

Vihatl claim as new, and desire to secure by Letters Patent, is-- v 1. The process of making hydrofluoric acid from hydrofluorsilieic acid, which consists in treating the hydrofiuorsilicic acid with an excess of a metallic compound, thereby producinga fiuorid, and then subjecting such fiuorid to the action of superheated steam, thereby liberating hydrofluoric acid, substantially as described.

-2. The process of making hydrofluoric acid from a mixture of hydroliuorsilicie acid and hydrofluoric acid, which consists in treating said mixture with anexeess of a metallic compound, thereby producing. a fiucrid, end then subjecting such fiuorid to the action of superheated steam, thereby liberating hydrofluoric acid, substantially as described.

CHAR-LES A. DOREMUS.

Witnesses: A

GEORGE J. GROTE, CHARLES B. Mnrniz. 

